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Percutaneous Closure of Congenital, Acquired, and Postinfarction Ventricular Septal Defects
Ventricular septal defects (VSDs) are the most common congenital heart disease, accounting for 25% of all congenital heart defects and occurring in 3 to 3.5 infants per 1000 live births. Congenital VSDs often close spontaneously in childhood or are otherwise treated. However, they may be left undiagnosed until adulthood. Previously undiagnosed VSDs can present in adulthood with a murmur, bacterial endocarditis, or cyanosis and exercise intolerance secondary to pulmonary hypertension. Alternatively, a VSD can be acquired during adulthood either after a myocardial infarction (MI), as a complication of cardiac surgery, or rarely after trauma to the chest. Classification and nomenclature of VSDs can be confusing to the nonpediatric practitioner. For simplicity, this chapter will refer to them by their most commonly used names. Figure 17–1 depicts the types of VSDs based on their location.
Locations of the common types of VSDs.
Perimembranous VSDs account for approximately 75% of all congenital VSDs. They are located in the midportion of the upper region of the ventricular septum and are related to the aortic and pulmonic valve. The second most common type of VSDs are the muscular VSDs, which are located entirely within the muscular portion of the septum; they account for approximately 10% of congenital VSDs. Although they may be found anywhere within the muscular septum, the majority are found in the midmuscular region. Anterior muscular defects are often multiple and may be referred to as “Swiss cheese” defects. Small VSDs, which are sometimes referred to as Henri-Louis Roger’s defects, are typically considered to be those defects that are less than one third the size of the aortic root. Because of their small size, little shunting occurs, and even if the defect does not close spontaneously, closure (surgical or percutaneous) may not be necessary. Other, less common VSDs such as supracristal (subarterial [aortic] or subpulmonic) and inlet defects are not discussed here, because they are not amenable to percutaneous closure.
Acquired VSDs are much less common than congenital VSDs. However, in the adult population, most congenital VSDs will have already been addressed in childhood. Therefore acquired VSDs do make up a substantial proportion of VSDs diagnosed during adulthood. In the largest study published on VSD closure in the adult population, 61% of the 28 patients had unrepaired congenital defects, 18% had postoperative residual patch margin defects, and 21% had acquired VSDs (either iatrogenic postoperative defects or defects that were secondary to trauma). Post-MI VSDs were not included in that study; however, another study from the same group published a few years earlier reported an additional 18 patients with post-MI VSDs who underwent transcatheter closure attempts.
VSDs secondary to MI septal rupture are much less common in the postreperfusion therapy era, occurring in only 0.2% to 0.34% of patients receiving thrombolysis for acute MI in the Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries (GUSTO-I) trial. These patients are usually acutely ill and may be in cardiogenic shock. If left untreated, almost 50% of patients die within the first week ; ultimately the mortality for patients treated medically approaches 100%. Early identification of the postinfarct VSD before the onset of irreversible organ failure caused by a low output state is crucial and requires a high index of suspicion. Transcatheter closure of these defects is feasible but offers a variety of challenges that will be discussed later in this chapter.
Iatrogenic VSDs are a rare entity that can be seen after surgical aortic or mitral valve replacement. These defects are usually located in the membranous septum and are usually hemodynamically insignificant. However, if closure of the defect is indicated, it is usually preferable to do so percutaneously, because repeat surgery can be complicated and associated with increased morbidity and mortality. An unusual type of iatrogenic VSD is a communication between the left ventricle and right atrium that is also known as the Gerbode defect. This type of communication can rarely be seen congenitally and has been described after mitral and aortic valve surgery, as well as secondary to infective endocarditis and trauma to the chest. These defects have historically been closed surgically; however, in cases of postsurgical Gerbode defects, repeat surgery can be challenging and it is possible to close the communication safely percutaneously. VSDs occurring after surgical myectomy in patients with hypertrophic obstructive cardiomyopathy have also been described, and closure of these defects percutaneously has been successful. Along the same lines, it is possible to have residual VSDs after surgical patch repair. The incidence of residual shunting after surgical repair can be anywhere between 5% and 25%, depending on the type of VSD repaired. These residual defects can be perimembranous, muscular, or apical, and if they are associated with a hemodynamically significant shunt, they need to be closed. Percutaneous closure offers a safe way to avoid the added morbidity and mortality associated with repeat sternotomy.
17.1
History of Ventricular Septal Defect Closure
Surgical closure has long been the gold standard for treatment of VSDs. However, despite advances in surgical technique, it continues to be associated with significant morbidity and mortality, especially when multiple defects are present or when repeat surgery is needed.
In 1987 the first percutaneous closure of a VSD was performed using the Rashkind double-umbrella device. The Rashkind device is a double disc composed of polyurethane foam on a hexagonal stainless steel frame. The device was initially designed for closure of patent ductus arteriosus or atrial–septal defects (ASDs). The authors were the first to attempt closure of post-MI VSDs and congenital VSDs with this device. They crossed the VSD from the left ventricle and advanced a guidewire to the right heart and then delivered the device via a delivery sheath from the venous route. Of the three patients with congenital VSDs, one patient died, one still had significant left-to-right shunt, and only one 44-year-old patient with a 5-mm VSD had a complete closure. After this first report, several other studies have shown that although this device could reduce the left-to-right shunting, the overall success rate and closure results were not satisfactory.
Other devices that have been used in the past included button devices, which have been shown to have a lower rate of complete closure and longer fluoroscopy time. The Bard Clamshell umbrella, which was originally designed for ASD closure, was also used for VSD closure. The device was redesigned by the manufacturer (Nitinol Medical Technologies, Boston, Mass.) and renamed the CardioSEAL device. The U.S. registry for this device showed good outcomes with a 92% success rate for 55 patients and only 8% adverse events. The U.S. Food and Drug Administration (FDA) has approved this device for use to close muscular VSDs in patients at high risk for surgical repair; however, the manufacturer of the device has gone out of business.
The Amplatzer muscular VSD occluder (St. Jude Medical, Plymouth, Minn.) is the most commonly used percutaneous VSD occlusion device ( Figure 17–2 ). It was first used experimentally in dog models in 1999, and use in humans quickly followed. It is a self-expandable, double-disc device made from a nitinol wire mesh. The wire thickness ranges from 0.003 to 0.005 inch. The two discs are linked together by a short (7-mm) cylindrical waist with a diameter that corresponds to the size of the VSD. The Amplatzer muscular VSD occluder is currently available in sizes ranging from 4 to 18 mm in 2-mm increments. The left and right ventricle discs are 8 mm larger than the waist (except for the 4-mm device, in which the discs are 9 mm in diameter). The discs and waist are filled with polyester fabric that is securely sewn to the device by a polyester thread. Outcomes with this device have been very promising. The U.S. registry reported a success rate approaching 90% for implantation and 92% for complete closure at one year. The device received FDA approval for closure of muscular VSDs in patients at high surgical risk.
The Amplatzer postinfarct VSD occluder is available in waist diameters 16 to 24 mm in 2-mm increments. It has a slightly different design from the muscular device. In the postinfarct device, the connecting waist is 10 mm long (to correspond to the thickness of the septum in adult patients) and the left- and right-sided discs are equal in size and 10 mm larger than the waist. The device has larger discs than the standard device in order to cover more of the friable ventricular septum and avoid device dislodgement and embolization. It is only available through the humanitarian device exemption (HDE) via the FDA for emergency or compassionate use in the United States.
The older Amplatzer membranous device has an asymmetric design with the two discs offset from each other. It was available in diameters of 4 to 18 mm in 1-mm increments to allow for more precise sizing. However, because of problems with complete heart block when using this original device, the continued use of this device in clinical trials has ceased. The European registry reported a complete heart block rate of 5% ; however, some centers have cited a rate as high as 22%. The Amplatzer membranous occluder 2 ( Figure 17–3 ) is a new membranous occluder device that is undergoing clinical trials outside the United States with the hope that its new design will have a lower rate of impact on the conduction system and subsequent heart block. In the new model, the left disc has an elliptical and concave shape that adapts to the left ventricular outflow tract (LVOT) and provides stability. In addition, the nitinol wire is considerably thinner, which decreases the rigidity of the device. The waist length was increased from 1.5 to 3 mm, and polyester patches were sewn into the discs to ensure rapid occlusion. The device is available in 9 waist diameters (from 4 to 10 mm in 1-mm increments, plus 12 and 14 mm).
17.2
Indications
The guidelines for VSD closure are listed in Box 17–1 . The 2008 American College of Cardiology (ACC)/American Heart Association (AHA) guidelines for adults with congenital heart disease give percutaneous closure of VSDs a IIb recommendation:
Device closure of a muscular VSD may be considered, especially if the VSD is remote from the tricuspid valve and the aorta, if the VSD is associated with severe left-sided heart chamber enlargement, or if there is pulmonary arterial hypertension. (Level of evidence: C).
BOX 17–1
Guidelines for Ventricular Septal Defect Closure
Class I
- 1.
Surgeons with training and expertise in CHD should perform VSD closure operations. (Level of evidence: C)
- 2.
Closure of a VSD is indicated when there is a pulmonary–to–systemic blood flow ratio (Qp/Qs) of 2 or more and clinical evidence of LV volume overload. (Level of evidence: B)
- 3.
Closure of a VSD is indicated when the patient has a history of infective endocarditis. (Level of evidence: C)
Class IIa
- 1.
Closure of a VSD is reasonable when net left-to-right shunting is present at a Qp/Qs greater than 1.5 with PA pressure less than two thirds of systemic pressure and PVR less than two thirds of systemic vascular resistance. (Level of evidence: B)
- 2.
Closure of a VSD is reasonable when net left-to-right shunting is present at a Qp/Qs greater than 1.5 in the presence of LV systolic or diastolic failure. (Level of evidence: B)
Class IIb
- 1.
Device closure of a muscular VSD may be considered, especially if the VSD is remote from the tricuspid valve and the aorta, if the VSD is associated with severe left-sided heart chamber enlargement, or if there is PAH. (Level of evidence: C)
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